1. Field of the Invention
The present invention relates to an automatic photometer for sample analysis.
The invention applies more particularly to automatic comparative measurements of the optical densities of solutions contained in a series of transparent cells.
The problem consists of analysing, by comparison with a test cell, chemical, biochemical or bacteriological reactions carried out in separate cells; given that the cells containing the samples are analyzed comparatively, the measurements must be done rapidly to obviate the influence of the time factor and, of course, the solutions must be protected from soils and contaminations.
2. Description of the Prior Art
Present known apparatus is of two types; on the one hand that including a fixed optical bench producing a measuring lightbeam into which the cells containing the samples are brought one after the other and, on the other hand, that including a fixed optical bench and an analysis cell likewise fixed situated in the measuring beam, each sample of solution being sent successively into the cell by pumping.
The first type of apparatus has the drawback of requiring complex mechanism due to the fact that each cell must be transported in space along three dimensions; as for equipment of the second type, it has the serious drawback of mixing the solutions in the analysis cell and of thus soiling the samples, which is troublesome both from the biological point of view and from the physical measurement point of view.
Lastly, the two types of equipment are slow and require a large number of manipulations which multiply the risks of contamination.
It is therefore an object of the invention to provide a photometer capable of carrying out measurements automatically, with rapidity and under optimal conditions of protection against soils, the apparatus forming furthermore a sterilizable assembly.